The present invention relates to a semiconductor memory and, particularly, the invention can suitably be used for a multi-port SRAM (Static Random Access Memory) that is capable of generating a physically unclonable function.
Various security threats/attacks to LSIs (Large Scale Integrated circuits) of microcomputers or the like, such as fraudulent access to them, their fraudulent imitations, and others, are reported. To protect the LSIs of microcomputers or the like and systems equipped with the LSIs against such attacks, a security technology using a device unique identifier PUF-ID (Physically Unclonable Function Identification), which leverages a function that is physically irreproducible, is developed.
In Patent Document 1, there are disclosed a technique that generates a PUF-ID using a memory and a technique that enhances resistance to physical attacks by means of a PUF generated using a memory. This technique generates a device unique PUF-ID as a cipher key by acquiring multiple values from multiple memory locations in one or more memories and reordering them. In the case of a SRAM memory, initial state values after the SRAM is powered on can be used to construct a PUF-ID. It is also described that a dual-port RAM is used and, by writing different pieces of data through both ports at the same time, memory cells exhibit a PUF-like behavior (paragraphs [0008] and [0043] in the same document).